Direct hydrazine borane fuel cells using non-noble carbon-supported polypyrrole cobalt hydroxide as an anode catalyst

Abstract

A novel proof-of-concept direct liquid fuel cell (DLFC) feeding on hydrazine borane (N₂H₄BH₃, HB) is developed. Non-noble carbon-supported polypyrrole cobalt hydroxide (C-PPY-Co(OH)₂) was used as an anode catalyst, which catalyzed HB electro-oxidation reactions to achieve an electron transfer number of 7.63 e⁻. The energy density of HB is 9947 W h kg⁻¹, exceeding that of traditional liquid fuels for DLFCs. The open circuit voltage of the fuel cell is 1.201 V, higher than that of direct methanol fuel cells (DMFCs) and direct hydrazine fuel cells (DHFCs). The fuel cell obtains a peak power density of 60 mW cm⁻², and the crossover current density of fuel is significantly lower than that of existing DLFCs. The electro-oxidation kinetics of HB on a Ni foam electrode is faster than that of a carbon paper. In addition, the mass transport resistance of the Ni foam electrode is 54 s cm⁻¹, much lower than that of the carbon paper electrode (231 s cm⁻¹).